To perform a DCE-CT scan, a small amount of a special dye (called "CT contrast medium") is injected by vein into the body. Several CT images are then taken over a few minutes to learn how much dye spreads outside of the tumor. This can show how much blood flows to and from the tumor. By performing DCE-CT scans after several weeks on treatment, researchers may learn if changes in blood flow may be a sign that the treatment is working.